Clinical Pearls & Morning Reports

By Carla Rothaus

Published March 27, 2019


What are the two different growth patterns that are used to classify mucinous ovarian carcinoma? 

Mucinous ovarian cancer is a rare tumor, probably accounting for 3% of all epithelial ovarian cancers. The only clinical risk factor associated with mucinous ovarian cancer is tobacco smoking. Mucinous tumors are characteristically diagnosed in patients who are younger than patients in whom other epithelial ovarian cancers are diagnosed. Read the latest review article here.

Clinical Pearls

Q: Does mucinous ovarian cancer tend to present at an early or late stage?

A: Sixty-five to 80% of mucinous ovarian cancers are diagnosed at an early stage, according to the classification of the International Federation of Gynecology and Obstetrics. Patients with serous ovarian cancer tend to present at an advanced stage, with intraperitoneal spread in more than 80% of cases. A potential explanation for this difference is that mucinous ovarian cancers are usually very large primary tumors (typically >15 cm in diameter) that generate symptoms while the disease is still localized to the ovary.

Q: How does survival for patients with mucinous ovarian carcinoma compare to that of patients with nonmucinous histologic subtypes?

A: Overall survival is higher for the majority of patients presenting with stage I disease than for those with nonmucinous histologic subtypes (hazard ratio, 0.52; 95% confidence interval [CI], 0.30 to 0.92). However, the trend is the inverse for women with stage III or IV mucinous ovarian cancer, who have significantly lower overall survival than women with nonmucinous histologic subtypes (hazard ratio, 2.81; 95% CI, 2.47 to 3.21).

Morning Report Questions

Q: What are the two different growth patterns that are used to classify mucinous ovarian carcinoma?

A: For decades, mucinous ovarian cancer was classified as grade 1, 2, or 3 according to the presence or absence of nuclear atypia and the proportion of solid glandular component. However, in 2014, the World Health Organization introduced a new diagnostic classification of mucinous ovarian carcinoma, with two categories according to the growth pattern: the expansile (confluent) subtype and the infiltrative subtype. The distinction between expansile and infiltrative subtypes is clinically important in stage I disease. The expansile growth pattern suggests a lower metastatic potential, and several, albeit small, studies have confirmed that the risk of relapse for women with stage I expansile mucinous ovarian cancer is extremely low. In contrast, infiltrative mucinous ovarian cancer is more aggressive, with at least 26% of women presenting with more advanced, nonlocalized disease at diagnosis; in 17 to 30% of patients who appear to have stage I disease, lymph-node metastases are detected (as compared with no women with expansile mucinous ovarian cancer). Even if the cancer is diagnosed at an early stage, the prognosis for women with infiltrative mucinous ovarian cancer is much poorer, with fatal relapses reported for 15 to 30% of patients with stage I disease.

Q: Describe aspects of the gene-expression profile of mucinous ovarian cancer.

A: The gene-expression profile of mucinous ovarian cancer is distinct from that of serous ovarian cancer. Mucinous ovarian cancers are not associated with BRCA mutations or defects in homologous recombination. The most frequent alterations are KRAS mutations (in 40 to 65% of cases), c-MYC amplifications (in 65%), HER2 amplifications (in 20 to 38%), and TP53 mutations (in 50 to 75%). In addition, other alterations have been identified at lower frequencies, such as homozygous deletions in CDKN2A/B (in 25% of cases), mutations in PI3KCA (in 13%), and mutations in PTEN, BRAF, FGFR, KIT, or STK11 (in 2 to 5%).

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